The best way to convert an expression sequence into a vector or an expression sequence of vectors into a matrix is to use angle-bracket operators:
f:= x-> <x | x+1>: # *row* vector
test:= <seq(f(i), i= 0..1, 0.1)>; #column of row vectors, i.e., a matrix
#You can plot a 2-column matrix without first extracting its x- and y-vectors:
plot(test, style= pointline);
#extraction of sequence of column vectors (don't know why this would be useful, but you asked):
ColVecs:= seq(test[..,k], k= 1..upperbound(test)[2]);
In your worksheet, you've repeatedly made the mistake of attempting to index a structure S with parentheses as in S(1). Square brackets should usually be used for indexing, as in S[1] and test[.., k]. With Vectors, Matrices, and Arrays (known collectively as rtables), in some cases you may use parentheses; this is known as programmer indexing. You used it correctly, albeit haphazardly, in your procedure f in your worksheet. I'd recommend that you stay away from this for the time being.
The Maple structures for which square-bracket indexing can be used for member extraction are expression sequences, lists, sets, tables, rtables, modules (which includes Records), and objects that overload `?[]`. Modules may also be indexed as A:-B rather than A[B] if B is explicitly an export of the module (in which case I recommend using the :- operator).